Collecting posture information to evaluate therapy

ABSTRACT

A medical device delivers a therapy to a patient. The medical device may identify posture events, e.g., periodically determine a posture of the patient and/or identify posture transitions by the patient, and associate each determined posture event with a current therapy parameter set. A value of at least one posture metric is determined for each of a plurality of therapy parameter sets based on the posture events associated with that therapy parameter set. A list of the therapy parameter sets is presented to a user, such as a clinician, for evaluation of the relative efficacy of the therapy parameter sets. The list may be ordered according to the one or more posture metric values to aid in evaluation of the therapy parameter sets. Where values are determined for a plurality of posture metrics, the list may be ordered according to the one of the posture metrics selected by the user.

This application claims the benefit of U.S. Provisional Application No.60/553,784, filed Mar. 16, 2004, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The invention relates to medical devices and, more particularly, tomedical devices that deliver therapy.

BACKGROUND

In some cases, an ailment may affect a patient's activity level or rangeof activities by preventing the patient from being active. For example,chronic pain may cause a patient to avoid particular physicalactivities, or physical activity in general, where such activitiesincrease the pain experienced by the patient. Other ailments that mayaffect patient activity include movement disorders and congestive heartfailure. When a patient is inactive, he may be more likely to berecumbent, i.e., lying down, or sitting, and may change postures lessfrequently.

In some cases, these ailments are treated via a medical device, such asan implantable medical device (IMD). For example, patients may receivean implantable neurostimulator or drug delivery device to treat chronicpain or a movement disorder. Congestive heart failure may be treated by,for example, a cardiac pacemaker.

SUMMARY

In general, the invention is directed to techniques for evaluating atherapy delivered to a patient by a medical device based on postureinformation. At any given time, the medical device delivers the therapyaccording to a current set of therapy parameters. The therapy parametersmay change over time such that the therapy is delivered according to aplurality of different therapy parameter sets. The medical device mayidentify posture events based on the posture of the patient, e.g.,periodically identify the patient's posture and/or posture transitions,and associate each identified posture event with the current therapyparameter set. A value of at least one posture metric is determined foreach of the therapy parameter sets based on the posture eventsassociated with that parameter set. A list of the therapy parameter setsand associated posture metrics is presented to a user, such asclinician, for evaluation of the relative efficacy of the therapyparameter sets. The list may be ordered according to the posture metricvalues to aid in evaluation of the therapy parameter sets. In thismanner, the user may readily identify the therapy parameter sets thatsupport the highest activity levels for the patient, and evaluate therelative efficacy of the parameter sets.

The medical device monitors a plurality of signals that are generated byrespective sensors and varies as a function of patient posture. Forexample, the medical device may monitor signals generated by a pluralityof accelerometers, gyros, or magnetometers. The sensors may be orientedsubstantially orthogonally with each other, and each sensor may besubstantially aligned with a body axis of the patient.

The medical device may identify a plurality of posture events based onthe one or more signals. In some embodiments, the medical deviceperiodically identifies the posture of the patient based on the one ormore signals, and the identified posture is stored as a posture event.The medical device may identify whether the patient is upright orrecumbent, e.g., lying down. In some embodiments in which sensors arelocated at a plurality of positions on or within the body of thepatient, the medical device may be able to identify additional postures,such as standing, sitting and recumbent. Example locations for thesensors include on or with the trunk of the patient, e.g., within animplantable medical device in the abdomen of the patient, andadditionally, in some embodiments, on or within an upper leg of thepatient. In some embodiments, the medical device identifies transitionsbetween postures, and stores indications of posture transitions asposture events.

As mentioned above, the medical device may associate each posture eventwith a current set of therapy parameters and, for each of a plurality oftherapy parameter sets used by the medical device over time, a value ofone or more posture metrics is determined. A posture metric value maybe, for example, an amount or percentage of time spent in a posturewhile a therapy parameter set is active, e.g., average amount of timeover a period of time, such as an hour, that a patient was within aparticular posture. In some embodiments, a posture metric value may bean average number of posture transitions over a period of time, e.g., anhour, that a particular therapy parameter sets was active.

In embodiments in which a plurality of posture metrics are determinedfor each therapy parameter set, an overall posture metric may bedetermined based on the plurality of posture metrics. The plurality ofposture metrics may be used as indices to select an overall posturemetric from a look-up table comprising a scale of potential overallposture metrics. The scale may be numeric, such as overall posturemetric values from 1-10.

The programming device or, in some external medical device embodiments,the medical device, presents a list of the plurality of parameter setsand associated posture metric values via a display. The programmingdevice may order the list according to the posture metric values. Wherevalues are determined for a plurality of posture metrics for each of thetherapy parameter sets, the programming device may order the listaccording to the values of a user selected one of the posture metrics.The programming device may also present other posture information to auser, such as a trend diagram of identified postures over time, or ahistogram or pie chart illustrating percentages of time that the patientassumed certain postures. The programming device may generate suchcharts or diagrams using posture events associated with a particular oneof the therapy parameter sets, or all of the posture events identifiedby the medical device.

In one embodiment, the invention is directed to a method in which aplurality of signals are monitored, each of the signals generated by arespective one of a plurality of sensors as a function of posture of apatient. A plurality of posture events are identified based on thesignals, and each of the posture events is associated with a therapyparameter set currently used by a medical device to deliver a therapy tothe patient when the posture event is identified. A value of a posturemetric is determined for each of a plurality of therapy parameter setsbased posture events associated with the therapy parameter sets.

In another embodiment, the invention is directed to a medical systemcomprising a medical device that delivers a therapy to a patient, aplurality of sensors, and a processor. Each of the plurality of sensorsgenerates a signal as a function of posture of the patient. Theprocessor that monitors the plurality of signals generated by thesensors, identifies a plurality of posture events based on the signals,associates each of the posture events with a therapy parameter setcurrently used by the medical device to deliver a therapy to the patientwhen the posture event is identified, and determines a value of aposture metric for each of a plurality of therapy parameter sets basedposture events associated with the therapy parameter sets.

In another embodiment, the invention is directed to a medical systemcomprising means for monitoring a plurality of signals, each of thesignals generated by a respective one of a plurality of sensors as afunction of posture of a patient, means for identifying a plurality ofposture events based on the signals, means for associating each of theposture events with a therapy parameter set currently used by a medicaldevice to deliver a therapy to the patient when the posture event isidentified, and means for determining a value of a posture metric foreach of a plurality of therapy parameter sets based posture eventsassociated with the therapy parameter sets.

In another embodiment, the invention is directed to a medical systemcomprising an implantable medical device and an external programmingdevice including a display. The implantable medical device delivers atherapy to a patient, monitors a plurality of signals, each of thesignals generated by a respective one of a plurality of sensors as afunction of posture of a patient, identifies a plurality of postureevents based on the signals, and associates each of the posture eventswith a current therapy parameter set. The external programming receivesinformation identifying a plurality of therapy parameter sets andassociated posture events from the implantable medical device viatelemetry, determines a value of a posture metric for each of aplurality of therapy parameter sets based on posture events associatedwith the therapy parameter sets, and presents a list of the plurality oftherapy parameter sets and posture metric values associated with thetherapy parameter sets via the display.

In another embodiment the invention is directed to a programming devicecomprising a telemetry circuit, a user interface including a display,and a processor. The processor receives information identifying aplurality of therapy parameter sets and associated posture events froman implantable medical device via the telemetry circuit, determines avalue of a posture metric for each of a plurality of therapy parametersets based on posture events associated with the therapy parameter sets,and presents a list of the plurality of therapy parameter sets andposture metric values associated with the therapy parameter sets via thedisplay.

In another embodiment, the invention is directed to a computer-readablemedium comprising program instructions. The program instructions cause aprogrammable processor to receive information identifying a plurality oftherapy parameter sets and associated posture events from an implantablemedical device, determine a value of posture metric for each of aplurality of therapy parameter sets based on activity levels associatedwith the therapy parameter sets, and present a list of the plurality oftherapy parameter sets and posture metric values associated with thetherapy parameter sets.

The invention is capable of providing one or more advantages. Forexample, a medical system according to the invention may provide aclinician with an objective indication of the efficacy of different setsof therapy parameters. Further, by displaying therapy parameter sets andassociated posture metric values in an ordered and, in some cases,sortable list, the medical system may allow the clinician to more easilycompare the relative efficacies of a plurality of therapy parametersets. The medical system may be particularly useful in the context oftrial neurostimulation for treatment of chronic pain, where the patientis encouraged to try a plurality of therapy parameter sets to allow thepatient and clinician to identify efficacious therapy parameter sets.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual diagram illustrating an example system thatincludes an implantable medical device that collects activityinformation according to the invention.

FIG. 2 is a block diagram further illustrating the example system andimplantable medical device of FIG. 1.

FIG. 3 is a block diagram illustrating an example memory of theimplantable medical device of FIG. 1.

FIG. 4 is a flow diagram illustrating an example method for collectingactivity information that may be employed by an implantable medicaldevice.

FIG. 5 is a block diagram illustrating an example clinician programmer.

FIG. 6 illustrates an example list of therapy parameter sets andassociated activity metric values that may be presented by a clinicianprogrammer.

FIG. 7 is a flow diagram illustrating an example method for displaying alist of therapy parameter sets and associated activity metric valuesthat may be employed by a clinician programmer.

DETAILED DESCRIPTION

FIG. 1 is a conceptual diagram illustrating an example system 10 thatincludes an implantable medical device (IMD) 14 that collectsinformation relating to the posture of a patient 12. In the illustratedexample system 10, IMD 14 takes the form of an implantableneurostimulator that delivers neurostimulation therapy in the form ofelectrical pulses to patient 12. However, the invention is not limitedto implementation via an implantable neurostimulator. For example, insome embodiments of the invention, IMD 14 may take the form of animplantable pump or implantable cardiac rhythm management device, suchas a pacemaker, that collects posture information. Further, theinvention is not limited to implementation via an IMD. In other words,any implantable or external medical device may collect activityinformation according to the invention.

In the illustrated example, IMD 14 delivers neurostimulation therapy topatient 12 via leads 16A and 16B (collectively “leads 16”). Leads 16may, as shown in FIG. 1, be implanted proximate to the spinal cord 18 ofpatient 12, and IMD 14 may deliver spinal cord stimulation (SCS) therapyto patient 12 in order to, for example, reduce pain experienced bypatient 12. However, the invention is not limited to the configurationof leads 16 shown in FIG. 1 or the delivery of SCS therapy. For example,one or more leads 16 may extend from IMD 14 to the brain (not shown) ofpatient 12, and MD 14 may deliver deep brain stimulation (DBS) therapyto patient 12 to, for example, treat tremor or epilepsy. As furtherexamples, one or more leads 16 may be implanted proximate to the pelvicnerves (not shown) or stomach (not shown), and IMD 14 may deliverneurostimulation therapy to treat incontinence, sexual dysfunction, orgastroparesis.

IMD 14 delivers therapy according to a set of therapy parameters, i.e.,a set of values for a number of parameters that define the therapydelivered according to that therapy parameter set. In embodiments whereIMD 14 delivers neurostimulation therapy in the form of electricalpulses, the parameters of each parameter set may include voltage orcurrent pulse amplitudes, pulse widths, pulse rates, duration, dutycycle, and the like. Further, each of leads 16 includes electrodes (notshown in FIG. 1), and a therapy parameter set may include informationidentifying which electrodes have been selected for delivery of pulses,and the polarities of the selected electrodes. Therapy parameter setsused by IMD 14 may include a number of parameter sets programmed by aclinician (not shown), and parameter sets representing adjustments madeby patient 12 to these preprogrammed sets.

System 10 also includes a clinician programmer 20. The clinician may useclinician programmer 20 to program therapy for patient 12, e.g., specifya number of therapy parameter sets and provide the parameter sets to IMD14. The clinician may also use clinician programmer 20 to retrieveinformation collected by IMD 14. The clinician may use clinicianprogrammer 20 to communicate with IMD 14 both during initial programmingof IMD 14, and for collection of information and further programmingduring follow-up visits.

Clinician programmer 20 may, as shown in FIG. 1, be a handheld computingdevice. Clinician programmer 20 includes a display 22, such as a LCD orLED display, to display information to a user. Clinician programmer 20may also include a keypad 24, which may be used by a user to interactwith clinician programmer 20. In some embodiments, display 22 may be atouch screen display, and a user may interact with clinician programmer20 via display 22. A user may also interact with clinician programmer 20using peripheral pointing devices, such as a stylus or mouse. Keypad 24may take the form of an alphanumeric keypad or a reduced set of keysassociated with particular functions.

System 10 also includes a patient programmer 26, which also may, asshown in FIG. 1, be a handheld computing device. Patient 12 may usepatient programmer 26 to control the delivery of therapy by IMD 14. Forexample, using patient programmer 26, patient 12 may select a currenttherapy parameter set from among the therapy parameter setspreprogrammed by the clinician, or may adjust one or more parameters ofa preprogrammed therapy parameter set to arrive at the current therapyparameter set.

Patient programmer 26 may include a display 28 and a keypad 30, to allowpatient 12 to interact with patient programmer 26. In some embodiments,display 28 may be a touch screen display, and patient 12 may interactwith patient programmer 26 via display 28. Patient 12 may also interactwith patient programmer 26 using peripheral pointing devices, such as astylus, mouse, or the like.

Clinician and patient programmers 20, 26 are not limited to thehand-held computer embodiments illustrated in FIG. 1. Programmers 20, 26according to the invention may be any sort of computing device. Forexample, a programmer 20, 26 according to the invention may be atablet-based computing device, a desktop computing device, or aworkstation.

IMD 14, clinician programmer 20 and patient programmer 26 may, as shownin FIG. 1, communicate via wireless communication. Clinician programmer20 and patient programmer 26 may, for example, communicate via wirelesscommunication with IMD 14 using radio frequency (RF) telemetry orinfrared techniques known in the art. Clinician programmer 20 andpatient programmer 26 may communicate with each other using any of avariety of local wireless communication techniques, such as RFcommunication according to the 802.11 or Bluetooth specification sets,infrared communication according to the IRDA specification set, or otherstandard or proprietary telemetry protocols.

Clinician programmer 20 and patient programmer 26 need not communicatewirelessly, however. For example, programmers 20 and 26 may communicatevia a wired connection, such as via a serial communication cable, or viaexchange of removable media, such as magnetic or optical disks, ormemory cards or sticks. Further, clinician programmer 20 may communicatewith one or both of IMD 14 and patient programmer 26 via remotetelemetry techniques known in the art, communicating via a local areanetwork (LAN), wide area network (WAN), public switched telephonenetwork (PSTN), or cellular telephone network, for example.

As mentioned above, IMD 14 collects patient posture information.Specifically, as will be described in greater detail below, IMD 14 maymonitors a plurality of signals, each of the signal generated by arespective sensor as a function of patient posture, and may identifyposture events based on the signals. IMD 14 may, for example,periodically identify the posture of patient 12 or transitions betweenpostures made by patient 12 as posture events. For example, IMD 14 mayidentify whether the patient is upright or recumbent, e.g., lying down,whether the patient is standing, sitting, or recumbent, or transitionsbetween such postures. IMD 14 may associate each determined postureevent with the therapy parameter set that is currently active when theposture event is identified.

Over time, IMD 14 uses a plurality of therapy parameter sets to deliverthe therapy to patient 12, and, as indicated above, may associate eachidentified posture event with a current set of therapy parameters. Foreach of a plurality of therapy parameter sets used by IMD 14 over time,a processor within IMD 14, clinician programmer 20, or patientprogrammer 26 may determine a value of one or more posture metrics basedon the posture events associated with that therapy parameter set. Aposture metric value may be, for example, an amount or percentage oftime spent in a posture while a therapy parameter set is active, e.g.,an average amount of time over a period of time, such as an hour, thatpatient 12 was within a particular posture. In some embodiments, aposture metric value may be an average number of posture transitionsover a period of time, e.g., an hour.

In some embodiments, a plurality of posture metric values are determinedfor each of the plurality of therapy parameter sets. In suchembodiments, an overall posture metric value may be determined. Forexample, the plurality of individual posture metric values may be usedas indices to identify an overall posture metric value from a look-uptable. The overall posture metric may selected from a predeterminedscale of activity metric values, which may be numeric, such as activitymetric values from 1-10.

One or more of IMD 14, clinician programmer 20, and patient programmer26 may determine the posture metric values as described herein. In someembodiments, IMD 14 determines and stores posture metric values for eachof a plurality of therapy parameter sets, and provides informationidentifying the therapy parameter sets and the associated posture metricvalues to, for example, programmer 20. In other embodiments, IMD 14provides information identifying the therapy parameter sets andassociated posture events to programmer 20, and the programmerdetermines the activity metric values for each of the therapy parametersets using any of the techniques described herein with reference to IMD14. In still other embodiments, IMD 14 provides signals output bysensors as function of patient posture to programmer 20, or theprogrammer receives the signals directed from the sensors via a wired orwireless link. In such embodiments, the programmer may identify postureevents and determine posture metric values based on the signals usingany of the techniques described herein with reference to IMD 14.

In any of these embodiments, programmer 20 may present a list of theplurality of parameter sets and associated posture metric values to theclinician via display 22. Programmer 20 may order the list according tothe posture metric values. Where values are determined for a pluralityof posture metrics for each of the therapy parameter sets, programmer 20may order the list according to the values of one of the posture metricsthat is selected by the clinician. Programmer 20 may also present otherposture information to the clinician, such as a trend diagram of postureover time, or a histogram or pie chart illustrating percentages of timethat the patient assumed certain postures. Programmer 20 may generatesuch charts or diagrams using posture events associated with aparticular one of the therapy parameter sets, or all of the postureevents identified over a period of time.

However, the invention is not limited to embodiments that includeprogrammer 20, or embodiments in which programmer 20 presents postureinformation to the clinician. For example, in some embodiments,programmer 26 presents posture information as described herein to one orboth of the clinician and patient 12. Further, in some embodiments, anexternal medical device comprises a display. In such embodiments, theexternal medical device both determines the activity metric values forthe plurality of therapy parameter sets, and presents the list oftherapy parameter sets and activity metric values.

FIG. 2 is a block diagram further illustrating system 10. In particular,FIG. 2 illustrates an example configuration of IMD 14 and leads 16A and16B. FIG. 2 also illustrates sensors 40A and 40B (collectively “sensors40”) that generate signals that vary as a function of patient posture.As will be described in greater detail below, IMD 14 monitors thesignals, and may identify posture events based on the signals.

IMD 14 may deliver neurostimulation therapy via electrodes 42A-D of lead16A and electrodes 42E-H of lead 16B (collectively “electrodes 42”).Electrodes 42 may be ring electrodes. The configuration, type and numberof electrodes 42 illustrated in FIG. 2 are merely exemplary. Forexample, leads 16A and 16B may each include eight electrodes 42, and theelectrodes 42 need not be arranged linearly on each of leads 16A and16B.

Electrodes 42 are electrically coupled to a therapy delivery module 44via leads 16A and 16B. Therapy delivery module 44 may, for example,include an output pulse generator coupled to a power source such as abattery. Therapy delivery module 44 may deliver electrical pulses topatient 12 via at least some of electrodes 42 under the control of aprocessor 46, which controls therapy delivery module 44 to deliverneurostimulation therapy according to a current therapy parameter set.However, the invention is not limited to implantable neurostimulatorembodiments or even to IMDs that deliver electrical stimulation. Forexample, in some embodiments a therapy delivery module 44 of an IMD mayinclude a pump, circuitry to control the pump, and a reservoir to storea therapeutic agent for delivery via the pump.

Processor 46 may include a microprocessor, a controller, a digitalsignal processor (DSP), an application specific integrated circuit(ASIC), a field-programmable gate array (FPGA), discrete logiccircuitry, or the like. Memory 48 may include any volatile,non-volatile, magnetic, optical, or electrical media, such as a randomaccess memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM),electrically-erasable programmable ROM (EEPROM), flash memory, and thelike. In some embodiments, memory 48 stores program instructions that,when executed by processor 46, cause IMD 14 and processor 46 to performthe functions attributed to them herein.

Each of sensors 40 generates a signal that varies as a function ofpatient posture. IMD 14 may include circuitry (not shown) thatconditions the signals generated by sensors 40 such that they may beanalyzed by processor 46. For example, IMD 14 may include one or moreanalog to digital converters to convert analog signals generated bysensors 40 into digital signals usable by processor 46, as well assuitable filter and amplifier circuitry. Although shown as including twosensors 40, system 10 may include any number of sensors.

Further, as illustrated in FIG. 2, sensors 40 may be included as part ofIMD 14, or coupled to IMD 14 via leads 16. Sensors 40 may be coupled toIMD 14 via therapy leads 16A and 16B, or via other leads 16, such aslead 16C depicted in FIG. 2. In some embodiments, a sensor 40 locatedoutside of IMD 14 may be in wireless communication with processor 46.

Sensors 40 may include a plurality of accelerometers, gyros, ormagnetometers that generate signals that indicate the posture of patient12. Sensors 40 may be oriented substantially orthogonally with respectto each other. In addition to being oriented orthogonally with respectto each other, each of sensors 40 used to detect the posture of patient12 may be substantially aligned with an axis of the body of patient 12.When accelerometers, for example, are aligned in this manner, themagnitude and polarity of DC components of the signals generate by theaccelerometers indicate the orientation of the patient relative to theEarth's gravity, e.g., the posture of patient 12. Further informationregarding use of orthogonally aligned accelerometers to determinepatient posture may be found in a commonly assigned U.S. Pat. No.5,593,431, which issued to Todd J. Sheldon.

Processor 46 may periodically determine the posture of patient 12, andmay store indications of the determined postures within memory 48 asposture events. Where system 10 includes a plurality of orthogonallyaligned sensors 40 located on or within the trunk of patient 12, e.g.,within IMD 14 which is implanted within the abdomen of patient 12 asillustrated in FIG. 1, processor 46 may be able to periodicallydetermine whether patient is, for example, upright or recumbent, e.g.,lying down. In embodiments of system 10 that include an additional oneor more sensors 40 at other locations on or within the body of patient12, processor 46 may be able to identify additional postures of patient12. For example, in an embodiment of system 10 that includes one or moresensors 40 located on or within the thigh of patient 12, processor 46may be able to identify whether patient 12 is standing, sitting, orlying down. Processor 46 may also identify transitions between posturesbased on the signals output by sensors 40, and may store indications ofthe transitions, e.g., the time of transitions, as posture events withinmemory 48.

Processor 46 may identify postures and posture transitions by comparingthe signals generated by sensors 40 to one or more respective thresholdvalues. For example, when patient 12 is upright a DC component of thesignal generated by one of a plurality of orthogonally alignedaccelerometers may be substantially at a first value, e.g., high or one,while the DC components of the signals generated by others of theplurality of orthogonally aligned accelerometers may be substantially ata second value, e.g., low or zero. When patient 12 becomes recumbent,the DC component of the signal generated by one of the plurality oforthogonally aligned accelerometers that had been at the second valuewhen the patient was upright may change to the first value, and the DCcomponents of the signals generated by others of the plurality oforthogonally aligned accelerometers may remain at or change to thesecond value. Processor 46 may compare the signals generated by suchsensors to respective threshold values to determine whether they aresubstantially at the first or second value, and to identify when thesignals change from the first value to the second value.

Processor 46 may identify posture events continuously or periodically,e.g., one sample of the signals output by sensors 40 every minute orcontinuously for ten minutes each hour. In some embodiments, processor46 limits recording of posture events to relevant time periods, i.e.,when patient 12 is awake or likely to be awake, and therefore likely tobe active. For example, patient 12 may indicate via patient programmer26 when patient is going to sleep or awake. Processor 46 may receivethese indications via a telemetry circuit 50 of IMD 14, and may suspendor resume recording of posture events based on the indications. In otherembodiments, processor 46 may maintain a real-time clock, and may recordposture events based on the time of day indicated by the clock, e.g.,processor 46 may limit posture event recording to daytime hours.

In some embodiments, processor 46 may monitor one or more physiologicalparameters of patient 12 via signals generated by additional sensors 40,and may determine when patient 12 is attempting to sleep or asleep basedon the physiological parameters. For example, processor 46 may determinewhen patient 12 is attempting to sleep by receiving an indication frompatient programmer 26, monitoring a physiological parameter indicativeof patient physical activity. In some embodiments, processor 46 maydetermine whether patient 12 is attempting to sleep by determiningwhether patient 12 remains in a recumbent posture for a threshold amountof time.

In other embodiments, processor 46 determines when patient 12 isattempting to fall asleep based on the level of melatonin in a bodilyfluid. In such embodiments, a sensor 40 may take the form of a chemicalsensor that is sensitive to the level of melatonin or a metabolite ofmelatonin in the bodily fluid, and estimate the time that patient 12will attempt to fall asleep based on the detection. For example,processor 46 may compare the melatonin level or rate of change in themelatonin level to a threshold level stored in memory 48, and identifythe time that threshold value is exceeded. Processor 46 may identify thetime that patient 12 is attempting to fall asleep as the time that thethreshold is exceeded, or some amount of time after the threshold isexceeded. Any of a variety of combinations or variations of theabove-described techniques may be used to determine when patient 12 isattempting to fall asleep, and a specific one or more techniques may beselected based on the sleeping and activity habits of a particularpatient.

In order to determine whether patient 12 is asleep, processor 46 maymonitor any one or more physiological parameters that discernibly changewhen patient 12 falls asleep, such as activity level, posture, heartrate, respiration rate, respiratory volume, blood pressure, blood oxygensaturation, partial pressure of oxygen within blood, partial pressure ofoxygen within cerebrospinal fluid, muscular activity, core temperature,arterial blood flow, and galvanic skin response. Processor 46 mayadditionally or alternatively monitor the variability of one or more ofthese physiological parameters, such as heart rate and respiration rate,which may discernible change when patient 12 is asleep. Further detailsregarding monitoring physiological parameters to identify when a patientis attempting to sleep and when the patient is asleep may be found in acommonly-assigned and co-pending U.S. patent application by KennethHeruth and Keith Miesel, entitled “DETECTING SLEEP,” which was assignedU.S. patent application Ser. No. 10/825,964 and filed Apr. 15, 2004, andis incorporated herein by reference in its entirety.

In other embodiments, processor 46 may record posture events in responseto receiving an indication from patient 12 via patient programmer 26.For example, processor 46 may record posture during times when patient12 believes the therapy delivered by IMD 14 is ineffective and/or thesymptoms experienced by patient 12 have worsened. In this manner,processor 46 may limit data collection to periods in which moreprobative data is likely to be collected, and thereby conserve a batteryand/or storage space within memory 48.

FIG. 3 illustrates memory 48 of IMD 14 in greater detail. As shown inFIG. 3, memory 48 stores information describing a plurality of therapyparameter sets 60. Therapy parameter sets 60 may include parameter setsspecified by a clinician using clinician programmer 20. Therapyparameter sets 60 may also include parameter sets that are the result ofpatient 12 changing one or more parameters of one of the preprogrammedtherapy parameter sets. For example, patient 12 may change parameterssuch as pulse amplitude, pulse frequency, or pulse width via patientprogrammer 26.

Memory 48 also stores thresholds 62 used by processor 46 to identifypostures of patient 12 and/or transitions between postures, as discussedabove. When processor 46 identifies a posture event 64 as discussedabove, processor 46 associates the posture event 64 with the current oneof therapy parameter sets 60, e.g., the one of therapy parameter sets 60that processor 46 is currently using to control delivery of therapy bytherapy module 44 to patient 12. For example, processor 46 may storedetermined posture event 64 within memory 48 with an indication of theparameter sets 60 with which they are associated. In other embodiments,processor 46 stores samples (not shown) of signals generated by sensors40 within memory 48 with an indication of the parameter sets 60 withwhich they are associated.

In some embodiments, processor 46 determines a value of one or moreposture metrics for each of therapy parameter sets 60 based on theposture events 63 associated with the parameter sets 60. Processor 46may store the determined posture metric values 66 within memory 48 withan indication as to which of therapy parameter sets 60 the determinedvalues are associated with. For example, processor 46 may determine anamount of time that patient 12 was in a posture when a therapy parameterset 60 was active, e.g., an average amount of time over a period of timesuch as an hour, as a posture metric 66 for the therapy parameter set60. Processor 46 may additionally or alternatively determine percentagesof time that patient 12 assumed one or more postures while a therapyparameter set was active as a posture metric 66 for the therapyparameter set 60. As another example, processor 46 may determine anaverage number of transitions over a period of time, such as an hour,when a therapy parameter set 60 was active as a posture metric 66 forthe therapy parameter set 60.

In some embodiments, processor 46 determines a plurality of posturemetric values 66 for each of the plurality of therapy parameter sets 60,and determines an overall posture metric value 66 for a parameter setbased on the values of the individual posture metrics for that parameterset. For example, processor 46 may use the plurality of individualposture metric values as indices to identify an overall posture metricvalue from a look-up table stored in memory 48. Processor 46 may selectthe overall posture metric value from a predetermined scale of posturemetric values, which may be numeric, such as posture metric values from1-10.

As shown in FIG. 2, IMD 14 includes a telemetry circuit 50, andprocessor 46 communicates with programmers 20, 26 via telemetry circuit50. In some embodiments, processor 46 provides information identifyingtherapy parameter sets 60 and posture metric values 66 associated withthe parameter sets to programmer 20, and programmer 20 displays a listof therapy parameter sets 60 and associated activity metric values 66.In other embodiments, as will be described in greater detail below,processor 46 does not determine posture metric values 66. Instead,processor 46 provides information describing posture events 64 toprogrammer 20 via telemetry circuit 50, and programmer 20 determinesposture metric values 66 for display to the clinician. Further, in otherembodiments, processor 46 provides samples of signals generated bysensors 40 to programmer 20 via telemetry circuit 50, and programmer 20may both identify posture events 64 and determine posture metric values66 based on the samples. In still other embodiments, one of programmers20, 26 receives one or more of the signals generated by sensors 40directly, and the programmer may both identify posture events 64 anddetermine posture metric values 66 based on the signals. Some externalmedical device embodiments of the invention include a display, and aprocessor of such an external medical device may both determine posturemetric values 66 and display a list of therapy parameter sets 60 andassociated posture metric values 66 to a clinician.

FIG. 4 is a flow diagram illustrating an example method for collectingposture information that may be employed by IMD 14. IMD 14 monitors aplurality of signals generated by sensors 40 as a function of theposture of patient 12 (70). For example, IMD 14 may monitor the DCcomponents of signals generated by a plurality of substantiallyorthogonally aligned accelerometers. Each of the accelerometers may besubstantially aligned with a respective axis of the body of patient 12.

IMD 14 identifies a posture event 64 (72). For example, IMD 14 mayidentify a current posture of patient 12 at a time when the signalsgenerated by sensors 40 are sampled, or may identify the occurrence of atransition between postures. IMD 14 identifies the current therapyparameter set 60, and associates the identified posture event 64 withthe current therapy parameter set 60 (74). For example, IMD 14 may storeinformation describing the identified posture event 64 within memory 48with an indication of the current therapy parameter set 60. IMD 14 maythen update one or more posture metric values 66 associated with thecurrent therapy parameter set 60, as described above (76).

IMD 14 may periodically perform the example method illustrated in FIG.4, e.g., may periodically monitor the posture signals (70), identifyposture events 64 (72), and associate the identified posture events 64with a current therapy parameter set 60 (74). As described above, IMD 14may only perform the example method during daytime hours, or whenpatient is awake and not attempting to sleep, and/or only in response toan indication received from patient 12 via patient programmer 26. IMD 14need not update posture metric values 66 each time a posture event 64 isidentified, e.g., each time the posture signals are sampled to identifythe posture of patient 12. In some embodiments, for example, IMD 14 maystore posture events 64 within memory, and may determine the posturemetric values 66 upon receiving a request for the values from clinicianprogrammer 20.

Further, in some embodiments, as will be described in greater detailbelow, IMD 14 does not determine the posture metric values 66, butinstead provides information describing posture events 64 to aprogramming device, such as clinician programmer 20 or patientprogrammer 26. In such embodiments, the programming device determinesthe posture metric values 66 associated with each of the therapyparameter sets 60. Additionally, as described above, IMD 14 need notidentify posture events 64. Instead, a programming device may receiveposture signals from IMD 14 or directly from sensors 40, and may bothidentify posture events 64 and determine posture metric values 66 basedon the samples.

FIG. 5 is a block diagram illustrating clinician programmer 20. Aclinician may interact with a processor 80 via a user interface 82 inorder to program therapy for patient 12, e.g., specify therapy parametersets. Processor 80 may provide the specified therapy parameter sets toIMD 14 via telemetry circuit 84.

At another time, e.g., during a follow up visit, processor 80 mayreceive information identifying a plurality of therapy parameter sets 60from IMD 14 via telemetry circuit 84, which may be stored in a memory86. The therapy parameter sets 60 may include the originally specifiedparameter sets, and parameter sets resulting from manipulation of one ormore therapy parameters by patient 12 using patient programmer 26. Insome embodiments, processor 80 also receives posture metric values 66associated with the therapy parameter sets 60, and stores the posturemetric values 66 in memory 86.

In other embodiments, processor 80 receives information describingposture events 64 associated with the therapy parameter sets 60, anddetermines values 66 of one or more posture metrics for each of theplurality of therapy parameter sets 60 using any of the techniquesdescribed above with reference to IMD 14 and FIGS. 2 and 3. In stillother embodiments, processor 80 receives the samples of the signalsoutput by sensors 40 from IMD 14, or directly from sensors 40, andidentifies posture events 64 and determines posture metric values 66based on signals using any of the techniques described above withreference to MD 14 and FIGS. 2 and 3.

Upon receiving or determining posture metric values 66, processor 80generates a list of the therapy parameter sets 60 and associated posturemetric values 66, and presents the list to the clinician. User interface82 may include display 22, and processor 80 may display the list viadisplay 22. The list of therapy parameter sets 60 may be orderedaccording to the associated posture metric values 66. Where a pluralityof posture metric values are associated with each of the parameter sets,the list may be ordered according to the values of the posture metricselected by the clinician. Processor 80 may also present other postureinformation to a user, such as a trend diagram of posture over time, ora histogram, pie chart, or other illustration of percentages of timethat patient 12 assumed certain postures. Processor 80 may generate suchcharts or diagrams using posture events 64 associated with a particularone of the therapy parameter sets 60, or all of the posture eventsrecorded by IMD 14.

User interface 82 may include display 22 and keypad 24, and may alsoinclude a touch screen or peripheral pointing devices as describedabove. Processor 80 may include a microprocessor, a controller, a DSP,an ASIC, an FPGA, discrete logic circuitry, or the like. Memory 86 mayinclude program instructions that, when executed by processor 80, causeclinician programmer 20 to perform the functions ascribed to clinicianprogrammer 20 herein. Memory 86 may include any volatile, non-volatile,fixed, removable, magnetic, optical, or electrical media, such as a RAM,ROM, CD-ROM, hard disk, removable magnetic disk, memory cards or sticks,NVRAM, EEPROM, flash memory, and the like.

FIG. 6 illustrates an example list 90 of therapy parameter sets andassociated posture metric values 66 that may be presented by clinicianprogrammer 20. Each row of example list 130 includes an identificationof one of therapy parameter sets 60, the parameters of the therapyparameter set, and values 66 associated with the therapy parameter setfor each of two illustrated posture metrics. Programmer 20 may orderlist 90 according to a user-selected one of the posture metrics.

The posture metrics illustrated in FIG. 6 are a percentage of timeupright, and an average number of posture transitions per hour. IMD 14or programmer 20 may determine the average number of posture transitionsper hour for one of the illustrated therapy parameter sets byidentifying the total number of posture transitions associated with theparameter set and the total amount of time that IMD 14 was using theparameter set. IMD 14 or programmer 20 may determine the percentage oftime upright for one of parameter sets 60 as the percentage of the totaltime that the therapy parameter set was in use that patient 12 wasidentified to be in an upright position.

FIG. 7 is a flow diagram illustrating an example method for displaying alist of therapy parameter sets 60 and associated posture metric values66 that may be employed by a clinician programmer 20. Programmer 20receives information identifying therapy parameter sets 60 andassociated posture events from IMD 14 (100). Programmer 20 thendetermines one or more posture metric values 66 for each of the therapyparameter sets based on the posture events 64 associated with thetherapy parameter sets (102). In embodiments in which programmer 20determines posture metric values 66, the clinician may be able tospecify which of a plurality of possible posture metric values 66 aredetermined. In other embodiments, IMD 14 determines the posture metricvalues 66, and provides them to programmer 20, or provides samples ofposture signals associated with therapy parameter sets to programmer 20for determination of posture metric values, as described above. Afterreceiving or determining posture metric values 66, programmer 20presents a list 90 of therapy parameter sets 60 and associated posturemetric values 66 to the clinician, e.g., via display 22 (104).Programmer 20 may order list 90 of therapy parameter sets 60 accordingto the associated posture metric values 66, and the clinician may selectthe posture metric that list 90 is ordered according to via a userinterface 82 (106).

Various embodiments of the invention have been described. However, oneskilled in the art will recognize that various modifications may be madeto the described embodiments without departing from the scope of theinvention. For example, although described herein primarily in thecontext of treatment of pain with an implantable neurostimulator, theinvention is not so limited. The invention may be embodied in anyimplantable medical device that delivers a therapy, such as a cardiacpacemaker or an implantable pump. Further, the invention may beimplemented via an external, e.g., non-implantable, medical device. Insuch embodiments, the external medical device itself may include a userinterface and display to present posture information to a user, such asa clinician or patient, for evaluation of therapy parameter sets.

As another example, the invention may be embodied in a trialneurostimulator, which is coupled to percutaneous leads implanted withinthe patient to determine whether the patient is a candidate forneurostimulation, and to evaluate prospective neurostimulation therapyparameter sets. Similarly, the invention may be embodied in a trial drugpump, which is coupled to a percutaneous catheter implanted within thepatient to determine whether the patient is a candidate for animplantable pump, and to evaluate prospective therapeutic agent deliveryparameter sets. Posture metric values collected by the trialneurostimulator or pump may be used by a clinician to evaluate theprospective therapy parameter sets, and select parameter sets for use bythe later implanted non-trial neurostimulator or pump. In particular, atrial neurostimulator or pump may determine values of one or moreposture metrics for each of a plurality of prospective therapy parametersets, and a clinician programmer may present a list of prospectiveparameter sets and associated posture metric values to a clinician. Theclinician may use the list to identify potentially efficacious parametersets, and may program a permanent implantable neurostimulator or pumpfor the patient with the identified parameter sets.

Further, the invention may be embodied as a computer-readable mediumthat includes instructions to cause a processor to perform any of themethods described herein. These and other embodiments are within thescope of the following claims.

1. A method comprising: monitoring a plurality of signals, each of thesignals generated by a respective one of a plurality of sensors as afunction of posture of a patient; identifying a plurality of postureevents based on the signals; associating each of the posture events witha therapy parameter set that was used by a medical device to deliver atherapy to the patient when the posture event was identified; and foreach of the plurality of therapy parameter sets, determining a value ofa posture metric based on the posture events associated with the therapyparameter set, the value of the posture metric indicating an efficacy ofthe therapy parameter set.
 2. The method of claim 1, wherein theplurality of sensors comprises a plurality of orthogonally alignedaccelerometers, and identifying a plurality of posture events comprisesidentifying a plurality of posture events based on a DC component ofeach of the signals generated by the plurality of accelerometers.
 3. Themethod of claim 1, wherein the plurality of sensors are positioned at aplurality of locations, each of locations one of on and within a body ofthe patient.
 4. The method of claim 1, wherein identifying a pluralityof posture events comprises periodically identifying a posture of thepatient.
 5. The method of claim 4, wherein periodically identifying aposture comprises periodically identifying whether the patient isupright or recumbent.
 6. The method of claim 4, wherein periodicallyidentifying a posture comprises periodically identifying whether thepatient is standing, sitting, or recumbent.
 7. The method of claim 4,wherein periodically identifying a posture comprises comparing at leastone of the signals to at least one threshold value.
 8. The method ofclaim 4, wherein determining a value of a posture metric for a therapyparameter set comprises determining at least one of an amount and apercentage of time spent in a posture based on the determined posturesassociated with the therapy parameter set.
 9. The method of claim 1,wherein identifying a plurality of posture events comprises identifyingposture transitions.
 10. The method of claim 9, wherein determining avalue of a posture metric for a therapy parameter set comprisesdetermining an average number of posture transitions over a period oftime based on the identified posture transitions associated with theparameter set.
 11. The method of claim 1, wherein identifying aplurality of posture events comprises: determining when the patient isawake; and identifying posture events while the patient is awake. 12.The method of claim 1, further comprising presenting a list of theplurality of therapy parameter sets and posture metric values associatedwith the therapy parameter sets.
 13. The method of claim 12, furthercomprising ordering the list of therapy parameter sets according to theassociated posture metric values.
 14. The method of claim 13, whereindetermining a value of a posture metric comprises determining a value ofeach of a plurality of posture metrics for each of a plurality oftherapy parameter sets based on posture events associated with thetherapy parameter sets, and ordering the list comprises ordering thelist according to a user selected one of the posture metrics.
 15. Themethod of claim 1, wherein determining a value of a posture metriccomprises: determining a value of each of a plurality of posturemetrics; and determining a value of an overall posture metric based onthe plurality of posture metric values.
 16. The method of claim 1,further comprising presenting a graphical representation of theidentified posture events.
 17. The method of claim 16, whereinpresenting a graphical representation comprises presenting at least oneof a trend diagram, a histogram and a pie chart based on the identifiedposture events.
 18. The method of claim 1, wherein the medical devicecomprises an implantable medical device.
 19. The method of claim 18,wherein the implantable medical device comprises at least one of animplantable neurostimulator and an implantable drug pump.
 20. The methodof claim 1, wherein the medical device comprises at least one of a trialneurostimulator and a trial pump.
 21. A medical system comprising: amedical device that delivers a therapy to a patient; a plurality ofsensors, each of the sensors generating a signal as a function ofposture of the patient; and a processor that monitors the plurality ofsignals generated by the sensors, identifies a plurality of postureevents based on the signals, associates each of the posture events witha therapy parameter set that was used by the medical device to deliver atherapy to the patient when the posture event was identified, and, foreach of the plurality of therapy parameter sets, determines a value of aposture metric based on the posture events associated with the therapyparameter set, the value of the posture metric indicating an efficacy ofthe therapy parameter set.
 22. The medical system of claim 21, whereinthe plurality of sensors comprises a plurality of orthogonally alignedaccelerometers, and the processor identifies the plurality of postureevents based on a DC component of each of the signals generated by theplurality of accelerometers.
 23. The medical system of claim 21, whereinthe plurality of sensors are positioned at a plurality of locations,each of locations one of on and within a body of the patient.
 24. Themedical system of claim 21, wherein medical device includes at leastsome of the sensors.
 25. The medical system of claim 21, wherein theprocessor periodically identifies a posture of the patient based on thesignals.
 26. The medical system of claim 25, wherein the processorperiodically identifies whether the patient is upright or recumbentbased on the signals.
 27. The medical system of claim 25, wherein theprocessor periodically identifies whether the patient is standing,sitting, or recumbent based on the signals.
 28. The medical system ofclaim 25, wherein processor compares at least one of the signals to atleast one threshold value, and periodically identifies a posture basedon the comparison.
 29. The medical system of claim 25, wherein theprocessor determines at least one of an amount and a percentage of timespent in a posture based on the determined postures associated with atherapy parameter set as a value of a posture metric for the therapyparameter set.
 30. The medical system of claim 21, wherein the processoridentifies posture transitions as posture events.
 31. The medical systemof claim 30, wherein the processor determines an average number ofposture transitions over a period of time as a value of a posture metricfor a therapy parameter set based on the identified posture transitionsassociated with the parameter set.
 32. The medical system of claim 21,wherein the processor determines when the patient is awake, andidentifies posture events while the patient is awake.
 33. The medicalsystem of claim 21, further comprising a display that presents a list ofthe plurality of therapy parameter sets and posture metric valuesassociated with the therapy parameter sets.
 34. The medical system ofclaim 33, further comprising a programming device that includes thedisplay, wherein the programming device orders the list of therapyparameter sets according to the associated posture metric values. 35.The medical system of claim 34, wherein the processor determines a valueof each of a plurality of posture metrics for each of a plurality oftherapy parameter sets based on posture events associated with thetherapy parameter sets, and the programming device orders the listaccording to a user selected one of the posture metrics.
 36. The medicalsystem of claim 21, wherein the processor determines a value of each ofa plurality of posture metrics, and determines a value of an overallposture metric based on the plurality of posture metric values.
 37. Themedical system of claim 21, further comprising a programming device thatincludes the display, wherein the programming device presents agraphical representation of the identified posture events via thedisplay.
 38. The medical system of claim 37, wherein the programmingdevice presents at least one of a trend diagram, a histogram and a piechart based on the identified posture events.
 39. The medical system ofclaim 21, wherein the medical device comprises an implantable medicaldevice.
 40. The medical system of claim 39, wherein the implantablemedical device comprises at least one of an implantable neurostimulatorand an implantable drug pump.
 41. The medical system of claim 21,wherein the medical device comprises at least one of a trialneurostimulator and a trial pump.
 42. The medical system of claim 21,wherein the processor comprises a processor of the medical device. 43.The medical system of claim 21, further comprising a programming device,wherein the processor comprises a processor of the programming device.44. A medical system comprising: means for monitoring a plurality ofsignals, each of the signals generated by a respective one of aplurality of sensors as a function of posture of a patient; means foridentifying a plurality of posture events based on the signals; meansfor associating each of the posture events with a therapy parameter setthat was used by a medical device to deliver a therapy to the patientwhen the posture event was identified; and means for determining, foreach of the therapy parameter sets, a value of a posture metric based onthe posture events associated with the therapy parameter set, the valueof the posture metric indicating an efficacy of the therapy parameterset.
 45. The medical system of claim 44, further comprising means forpresenting a list of the plurality of therapy parameter sets and posturemetric values associated with the therapy parameter sets.
 46. Themedical system of claim 45, further comprising means for ordering thelist according to the posture metric values.
 47. The medical system ofclaim 46, further comprising means for determining a value of each of aplurality of posture metrics for each of a plurality of therapyparameter sets based on posture events associated with the therapyparameter sets, wherein the means for ordering the list comprises meansfor ordering the list according to a user selected one of the posturemetrics.
 48. A medical system comprising: an implantable medical devicethat that delivers a therapy to a patient, monitors a plurality ofsignals, each of the signals generated by a respective one of aplurality of sensors as a function of posture of a patient, identifies aplurality of posture events based on the signals, and associates each ofthe posture events with a therapy parameter set that was used to controldelivery of the therapy when the posture event was identified; and anexternal programming device that: includes a display, receivesinformation identifying a plurality of therapy parameter sets andassociated posture events from the implantable medical device viatelemetry, determines, for each of a plurality of therapy parametersets, a value of a posture metric based on the posture events associatedwith the therapy parameter set, the value of the posture metricindicating an efficacy of the therapy parameter set, and presents a listof the plurality of therapy parameter sets and posture metric valuesassociated with the therapy parameter sets via the display forcomparison of the efficacies of the plurality of therapy parameter sets.49. The medical system of claim 48, wherein the implantable medicaldevice determines when the patient is awake, and identifies postureevents while the patient is awake.
 50. The medical system of claim 49,wherein the implantable medical device periodically identifies posturesas posture events, and wherein, for each of the therapy parameter sets,the external programming device determines at least one of an amount anda percentage of time spent in a posture based on the determined posturesassociated with a therapy parameter set as a value of a posture metricfor the therapy parameter set.
 51. The medical system of claim 48,wherein the implantable medical device identifies posture transitions asposture events, and wherein, for each of the therapy parameter sets, theexternal programming device determines an average number of posturetransitions over a period of time as a value of a posture metric for atherapy parameter set based on the identified posture transitionsassociated with the parameter set.
 52. The medical system of claim 48,wherein the programming device orders the list of therapy parameter setsaccording to the associated posture metric values.
 53. The medicalsystem of claim 52, wherein the programming device determines a value ofeach of a plurality of posture metrics for each of the plurality oftherapy parameter sets based on posture events associated with thetherapy parameter sets, receives a selection of one of the posturemetrics from a user, and orders the list according to the user selectedone of the posture metrics.
 54. The medical system of claim 48, whereinthe implantable medical device comprises at least one of an implantableneurostimulator and an implantable drug pump.
 55. The medical system ofclaim 48, further comprising the plurality sensors, wherein sensorscomprise a plurality of accelerometers, and the implantable medicaldevice identifies a plurality of posture events based on a DC componentof each of the signals generated by the plurality of accelerometers. 56.The medical system of claim 55, wherein at least some of the sensor areincluded within the implantable medical device.
 57. The medical systemof claim 56, wherein the sensors are located a plurality of locations,each of the locations one of on and within a body of the patient.
 58. Aprogramming device comprising: a telemetry circuit; a user interfaceincluding a display; and a processor that receives informationidentifying a plurality of therapy parameter sets and associated postureevents from an implantable medical device via the telemetry circuit,determines, for each of a plurality of therapy parameter sets, a valueof a posture metric based on the posture events associated with thetherapy parameter set, the value of the posture metric indicating anefficacy of the therapy parameter set, and presents a list of theplurality of therapy parameter sets and posture metric values associatedwith the therapy parameter sets via the display for comparison of theefficacies of the plurality of therapy parameter sets.
 59. Theprogramming device of claim 58, wherein the processor orders the list oftherapy parameter sets according to the associated posture metricvalues.
 60. The programming device of claim 59, wherein the processordetermines a value of each of a plurality of posture metrics for each ofthe plurality of therapy parameter sets based on posture eventsassociated with the therapy parameter sets, receives a selection of oneof the posture metrics from a user via the user interface, and ordersthe list according to the user selected one of the posture metrics. 61.A computer-readable medium comprising instructions that cause aprogrammable processor to: receive information identifying a pluralityof therapy parameter sets and associated posture events from animplantable medical device; for each of a plurality of therapy parametersets, determine a value of posture metric based on the posture eventsassociated with the therapy parameter set, the value of the posturemetric indicatin an efficacy of the therapy parameter set; and present alist of the plurality of therapy parameter sets and posture metricvalues associated with the therapy parameter sets for comparison of theefficacies of the plurality of therapy parameter sets.